The dungeness crab fishery in the US represents a $170 million market, but you may have seen in the headlines that this year’s crab pots will remain empty and fishing vessels are staying in their harbors. The root of the problem can be traced back to Pseudo-nitzschia, a common type of phytoplankton which produces a toxin called domoic acid.

Pseudo-nitzschia cells in long chains.  Credit: UCSC

Domoic acid is a neurotoxin that causes Amensic Shellfish Poisoning (ASP). In other words, when birds and mammals like us eat it, the toxin gets into our brain and causes seizures and death. The toxin accumulates in organisms that feed on phytoplankton which is in turn transferred to organisms that eat them (sea lions, crabs, etc.) In 1961, Californians reported “crazed seabirds” which inspired Alfred Hitchcock’s film The Birds (1963); we now believe that this was the result of domoic acid poisoning. It has becoming increasingly common for residents of the region to see birds “acting drunk” or sea lions having seizures on the beach. They are really suffering from domoic acid poisoning and have a very high risk of death.

Sea Lion Recovering from Domoic Acid Poisoning
Credit: The Marine Mammal Center

This summer, the coast of California experience an unprecedented bloom of Pseudo-nitzschia. Fortunately for us, our governmental organisations closely monitor concentrations of the toxin in our seafood, but this has led to economic troubles with closures such as the dungeness crab fishery. Marine mammal centers attempt to nurse sea lions back to health but not all of them make it.

Much about domoic acid and Pseudo-nitzschia remains unknown, but scientists are working hard to try to understand these toxic phytoplankton blooms and be able to predict their occurrence. Dr. Raphael Kudela and the University of California – Santa Cruz made a great two-part video series to educate the public about this year’s bloom and how scientists are monitoring it (below). Although we continue to suffer from the effects of this year’s blooms, hopefully they were able to learn a lot from it.